choose new controller for new install (4.0) system

I have to decide between two REAL raid controllers (LSI crossflash firmware) for my Lab Home Server, i found two interesteng model used on ebay:

1- IBM M1015 (more cheap but no cache no bbu) performance??
2- IBM M5015 but without BBU (with 512mb cache) cheap
2- IBM M5014 but without BBU (with 256mb cache) cheap

Some perole not have recommended the 5014 model (same 5015 but 1/2 memory cache)

Does anyone know if I can still enable the cache on the second model without BBU???

some performance on your system??

N.B: in the lab home server have UPS system and for now no bbu needed (i think...)

tnks